Each barn is going to be designed differently depending on how much land you have to work with. There are a couple of things to think about when designing your paddocks. The first one is how many horses are you going to have on your property? We have forty horses on our farm and we have a lot of different paddocks.
One of the biggest mistakes that some barn owners make is that they don't create enough paddocks in the beginning and find themselves in many situations that they didn't need to be in. In many cases they will lose boarders because of the lack of flexibility if things are not going well in a herd. I have had many people come to my barn over the years that left the place they were at because their horse was either losing weight because he couldn't get to the hay, or continually getting beat up. I have had horses come here that were extremely stressed out because of the previous setting they were placed in with no place to go. Some horses just don't well in certain herds and they need to be placed in a herd situation that will best fit their personality otherwise is creates many more problems for the horse.
At our barn the largest herd size is six horses. We have never gone over that number and it works well for us. It is not too big and very manageable for the boarders when they want to go out and get their horse out of the paddock. We have quite a few different groups of horses at our barn and they stem from two horses together all the way up to six horses.
One of the things to think about when designing your paddocks is your clients. For many of them the thought of going out into a herd of ten to fifteen horses might completely overwhelm them or scare them. Making your barn boarder friendly is something that will help make your job easier in the long run. Remember that many of your boarders will not have the confidence that you have when it comes to going out to grab a horse out of a herd and some of them will need some educating on how to do it safely. My thought is that you can never have too many paddocks and you will be surprised how quickly you fill them up. You will never regret building more instead of less.
Thank you for the great question!